2,6-Dichloro­pyridine-3,5-dicarbonitrile

In the crystal, essentially planar (r.m.s. deviation = 0.003 Å) mol­ecules of the title compound, C7HCl2N3, form chains along the b axis by means of C—H⋯N inter­actions. These chains are further linked into layers parallel to the ab plane by C—Cl⋯N inter­actions

3,9-Diisopropyl-2,4,8,10-tetra­thia­spiro­[5.5]undeca­ne

The mol­ecule of the title compound, C13H24S4, has C2 symmetry and it crystallizes as a racemate. The structure displays two six-membered rings exhibiting chair conformations, with the isopropyl substituents in equatorial positions. In the crystal structure, weak inter­molecular C—H⋯S inter­actions are observed, leading to a channel-like arrangement along the c axis

Cryptands by One-Pot Homoacetylenic Cu-Catalyzed Coupling -Synthesis, Structure and Properties

This review presents the synthesis of macrobicyclic compounds built from triphenylmethane, triphenylphosphine oxide units and other three-dimensional molecules with an aromatic core, as well as some fullerene precursors and buta-1,3-diynediyl spacers. The dependence of the coupling yield on the solvent, catalysts (Cu+ and/or Cu2+) and presence of oxygen is also addressed. The formation of inclusion complexes of these cage molecules with appropriately sized neutral guests such as solvent molecules (acetonitrile, benzene, dichloromethane, chloroform), cubane, benzyl cyanide and structural information of the host derivatives are also reviewed

Cryptands and bismacrocycles with cyanuric and isocyanuric units: synthesis and structural investigations

Hay synthesis of cryptands and bismacrocycles starting from tripodands with cyanuric and isocyanuric cores is reported. The structure of the compounds is revealed by X-ray diffraction, NMR spectrometry and MS investigations. DNMR experiments carried out with bismacrocycles indicated the flipping of the rings and the free-energy barrier for the conformational process could be determined in one case. (C) 2012 Elsevier Ltd. All rights reserved

Synthesis of Podands with Cyanurate or Isocyanurate Cores and Terminal Triple Bonds

The synthesis of podands with cyanuric or isocyanuric acid cores and oligoethyleneoxy pendant arms exhibiting terminal triple bonds or brominated triple bonds is reported. The starting material for cyanuric acid derived podands is commercially available cyanuric acid, while the isocyanuric derivatives are obtained by thermal isomerization of the corresponding cyanurates

Synthesis, Structural Analysis, and Chiral Investigations of Some Atropisomers with EE-Tetrahalogeno-1,3-butadiene Core

The atropenantiomers of stable 1,2,3,4-tetrahalo-1,3-butadiene derivatives (where halogeno stands for bromine or iodine) were separated with use of chiral HPLC. The barriers for the enantiomerization process were determined on-line by dynamic HPLC (DHPLC) or off-line by classical kinetic measurements. In the case of the tetrachloro compound, the barrier was too low for DHPLC and its value was obtained by dynamic NMR experiments. The obtained barriers for chloro, bromo, and iodo derivatives correlate with the van der Waals radii of the halogens. The absolute configuration of the isolated enantiomers of the tetraiodo and tetrabromo compounds was assigned by comparison of the experimental and conformations averaged calculated VCD spectra. The identification of a signature band of the absolute configuration of the butadiene core, the sign and location of which are independent from the different conformations and substituents, allowing the safe assignment of the absolute configuration of the enantiomers of chiral 1,3-butadienes, is also reported

Synthesis and Stereochemistry of New Bis(1,3-Oxathian-2-yl) Derivatives: Epimerisation and Chair–Twist Equilibria

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Stereogenic properties of spiranes combined with four equivalent conventional centres of chirality

Derivatives of the tri-spirane pentaerythritoxy-cyclophosphazene compound, 1, have been used to investigate the stereogenic properties of spiranes combined with four equivalent conventional centres of chirality. In compound 1 the two inner rings are carbocyclic and symmetrical and the two outer rings are cyclotriphosphazenes substituted in different positions to provide the conventional centres of chirality. The case of combining spiranes with four equivalent centres of chirality has been investigated by the reaction of 1 with dimethylamine in a 1 : 8 molar ratio to give four diastereoisomeric products, in which the two cyclophosphazene rings are non-geminally di-substituted in either cis or trans configurations; viz. the cis–cis ( 2a), cis–trans ( 2b) and two trans–trans substituted dimethylamine derivatives 2c and 2d. The structure and stereogenic properties of compound 2a (C2 symmetry) have been characterized previously by both X-ray crystallography and 31P NMR spectroscopy on addition of a chiral solvating agent (CSA) and the structures and stereogenic properties of compounds 2b (C1) and 2d (C2) have been similarly characterized in this work. The structure of compound 2c has been characterised by X-ray crystallography and found to be meso with the relatively rare S4 symmetry. The four diastereoisomeric products 2a–2d represent all the possible stereochemical isomers of a spirane combined with four equivalent conventional centres of chirality